In related art, in all of microwave heating devices of this type, electric devices have been designed for destination places according to the commercial power supply voltages of countries all over the world.
A microwave oven as a related-art microwave heating device commonly configured to: once convert the commercial power supply to a high voltage by a high-voltage boosting transformer; generate a high DC voltage by a voltage doubler rectification circuit; drive a microwave self-oscillation device called a magnetron by the generated high DC voltage to radiate a microwave into a cavity enclosed by a metal; and heat food by dielectric heating by the microwave (for example, see Patent Document 1). At this time, for example, in the case of products for Japan, it is necessary to design the microwave oscillation circuit and select electric components with the input voltage as 100 V AC. In UK, the input voltage is mainly a commercial power supply of 240 V, and it is necessary to make a similar design and electric component selections according to the voltage.
For example, FIG. 5 is an overall circuit diagram of a related-art microwave heating device. The microwave heating device includes a commercial power supply 1 and a safety device 13 for preventing microwave leakage. The safety device 13 includes a fuse 12 disposed on the hot side of a two-port line derived from the commercial power supply 1, a microswitch 10 disposed between the hot line and the cold line on the subsequent stage, and a microswitch 11 disposed on the cold line on the further subsequent stage. The safety device 13 has a fail-safe mechanism so that the microwave does not leak to the outside of the cavity when the door is open. The technical regulation also strictly regulates the model.
On the subsequent stage of the safety device 13, an oven lamp 14, a wave agitating motor 15 and a cooling fan motor 16 are disposed and constitute a plurality of loads 6. For the loads 6, a relay 17, a relay 18 and a relay 19 are disposed in series, respectively, and opening and closing is controlled by a controller 2 whenever necessary. A high-voltage transformer 21 boosts commercial power at it input to a high voltage on the order of Kv as the commercial power. Power charge to the high-voltage transformer 21 is controlled by the opening and closing of a relay 20. The output of the high-voltage transformer 21 undergoes a half-wave voltage doubler rectification by a high-voltage circuit 22 including a diode 23 and a capacitor 24, is converted to a high DC voltage of approximately 7 Kv at the time of startup and of approximately 4 Kv at the time of steady oscillation, and is applied to a magnetron 25, so that a microwave of approximately 2.45 kHz is output.
Patent Document 1: JP-A-H01-112697